Using the lizard, anolis carolinensis, as a model system, I propose to investigate further the possible evolutionary origins of physiological and psychological influences upon reproductive behavior as well as how these behavioral controlling mechanisms might function to adapt organisms to their environment. To this end, studies of the physiological control of species-typical behavior and the stimulus control of hormone secretion are planned. Descriptive and analytic studies of the reproductive behavior and reproductive isolating mechanisms of sympatric species, including experiments on individual and species recognition, the role of the dewlap in interspecific communication, and display variation and sexual selection, will be conducted both in the field and in the laboratory. Research on the psychobiology of reproduction of snakes and turtles is also proposed. Specifically, the hormonal regulation of male reproductive behavior in snakes will be investigated and the hormonally-dependent male and female sex pheromones critical in the coordination of reproductive behavior isolated and characterized. Studies designed to test in the field hypotheses arising from laboratory research on pheromone communication in snakes and turtles are also proposed.